Baroness Bakewell, 82, who is chairing the Wellcome Book Prize judging panel, said she was "alarmed" by the condition in young people.

In an interview with The Sunday Times she pointed out that eating disorders do not occur in countries ravaged by poverty or Syrian refugee camps and instead suggested it was a sign of the "overindulgence of our society".

On her Twitter account, she said she is "deeply sorry".

In a series of tweets, she wrote: ".@JDBakewell I have spent 6 hours answering tweets I did not expect the ST to quote my views on anorexia.....

She added: "I am tired now and taking a break from Twitter. Goodnight everyone."

Baroness Bakewell told the newspaper: "I am alarmed by anorexia among young people, which arises presumably because they are preoccupied with being beautiful and healthy and thin.

"No-one has anorexia in societies where there is not enough food. They do not have anorexia in the camps in Syria. I think it's possible anorexia could be about narcissism."

She added: "To be unhappy because you are the wrong weight is a sign of the overindulgence of our society, over-introspection, narcissism, really."

Earlier this year, David Cameron pledged to ensure teenagers with eating disorders receive treatment more quickly.

From 2017/18 a new waiting time measure will track the proportion of patients being seen within a month of referral, or within a week for urgent cases.

Baroness Bakewell also suggested that, while she was pleased to see the stigma around discussing mental health was fading, counselling and psychotherapy - including treatment for children - "can get out of hand".

The president of Birkbeck, University of London, said that asking people "Are you really happy?" gave them a chance to consider anxieties that had not previously crossed their mind.

The Wellcome Book Prize rewards the best book, fiction or non-fiction, linked to medicine, health or illness.

The shortlist will be announced on Monday and the winner crowned on April 25.